4'-Methyl-4,5'-bithiazole-based correctors of defective delta F508-CFTR cellular processing.

The synthesis and Delta F508-CFTR corrector activity of a 148-member methylbithiazole-based library are reported. Synthetic routes were devised and optimized to generate methylbithiazole analogs in four steps. Corrector potency and efficacy were assayed using epithelial cells expressing human Delta F508-CFTR. These structure-activity data establish that the bithiazole substructure plays a critical function; eight novel methylbithiazole correctors were identified with low micromolar potencies.

Isoxazolopyrimidines as Novel ΔF508-CFTR Correctors.

Using a cell-based high-throughput screen, we identified isoxazolo[5,4-d]pyrimidines as novel small-molecule correctors of the cystic fibrosis mutant protein ΔF508-CFTR. 22 Isoxazolo[5,4-d]pyrimidine analogues were synthesized and tested. Synthesis of the key intermediate, 5-amino-3-arylisoxazole-4-carboxamide, was accomplished by nitrile oxide cycloaddition to (2-amino-1-cyano-2-oxoethyl)sodium. Formation of 3-arylisoxazolo-[5,4-d]pyrimidin-4(5H)-one and chlorination gave 4-chloro-3-arylisoxazolo[5,4-d]pyrimidine. Finally, functionalization at C-4 of the pyrimidine ring by nucleophilic substitution gave the targeted isoxazolo[5,4-d]pyrimidines. Six of the reported analogues had low micromolar potency for increasing halide transport in ΔF508-CFTR cells.

Potent s-cis-locked bithiazole correctors of DeltaF508 cystic fibrosis transmembrane conductance regulator cellular processing for cystic fibrosis therapy.

N-(5-(2-(5-Chloro-2-methoxyphenylamino)thiazol-4-yl)-4-methylthiazol-2-yl)pivalamide 1 (compound 15Jf) was found previously to correct defective cellular processing of the cystic fibrosis protein DeltaF508-CFTR. Eight C4'-C5 C,C-bond-controlling bithiazole analogues of 1 were designed, synthesized, and evaluated to establish that constraining rotation about the bithiazole-tethering has a significant effect on corrector activity. For example, constraining the C4'-C5 bithiazole tether in the s-cis conformation [N-(2-(5-chloro-2-methoxyphenylamino)-7,8-dihydro-6 H-cyclohepta[1,2- d:3,4- d']bithiazole-2'-yl)pivalamide, 29] results in improved corrector activity. Heteroatom placement in the bithaizole core is also critical as evidenced by the decisive loss of corrector activity with s-cis constrained N-(2-(5-chloro-2-methoxyphenylamino)-5,6-dihydro-4 H-cyclohepta[1,2- d:3,4- d']bithiazole-2'-yl)pivalamide 33. In addition, computational models were utilized to examine the conformational preferences for select model systems. Following our analysis, the " s-cis-locked" cycloheptathiazolothiazole 29 was found to be the most potent bithiazole corrector, with an IC50 of approximately 450 nM.